"There are 3 million jobs available in America that are not filled because too many of our people don't have the skills for those jobs."

Sen. Marco Rubio, in a speech at CPAC

The ruling

We turned to data from the Bureau of Labor Statistics, the federal government's scorekeeper on employment data.

The 3 million figure Rubio used comes from a monthly survey called the Job Openings and Labor Turnover Survey, or JOLTS. The most recent seasonally adjusted data cover January 2013 and showed that there were just under 3.7 million job openings in January, up slightly from 3.6 million in December 2012.

But Rubio specifically said that "there are 3 million jobs available in America that are not filled because too many of our people don't have the skills for those jobs." A close look at the survey reveals it doesn't actually support that thesis.

The bureau's official definition of a "job opening" is "a specific position of employment to be filled at an establishment" that satisfies these conditions: "there is work available for that position, the job could start within 30 days, and the employer is actively recruiting for the position."

However, there are always job openings — even in a healthy economy. In a phenomenon known as "churn," people change jobs. Just because their old job is unoccupied when the BLS takes its monthly data snapshot doesn't necessarily mean that the employer is having trouble filling the job, or finding the skills of the applicants lacking. Rather, the employer could simply be going through the process of hiring, with the job filled a month later.

Over the past decade, the December monthly totals for job openings have ranged from 2.9 million to 4.4 million.

So, if Rubio means to say that 3 million of the 3.7 million job openings are open due to skill shortfalls, he has no way of knowing that because that sort of data is not collected. The same is true if he was simply using "3 million" as shorthand for "3.7 million."

The data from this survey "has important limitations," said Steven J. Davis, an economist at the University of Chicago Booth School of Business, because it "provides little information about the distribution of vacancy durations" and "no direct information about the reason why some job openings take a long time to fill."

So what can we say about the scale of the skills mismatch? It boils down largely to a battle of anecdotes.

Economists we consulted agreed that divergence between applicants' job skills and the ones employers are seeking is part of the issue, particularly for high-skill jobs. But it's probably not the only reason.

For instance, there appears to be a "hiring paralysis" among employers who are acting with unusual caution because they are uncertain whether the economy will remain strong rather than stagnating, according to economists and hiring professionals quoted in the New York Times earlier this year.